Fuel system



June 18, 1968 F. A. WYCZALEK FUEL SYSTEM Filed Sept. 16, 1965 AIR PUMP ONE ORIFICE AIR FLOW l N VEN TOR. fiqydfldyaza/e BY United States Patent 3,388,898 FUEL SYSTEM Floyd A. Wyczalek, Birmingham, Mich., assignor to General Motors Corporation, Detroit, Mich., a corporation of Delaware Filed Sept. 16, 1965, Ser. No. 487,756 8 (Ilaims. (Cl. 261-24) ABSTRACT OF THE DISCLOSURE An internal combustion engine fuel system including a nozzle adapted to discharge fuel for mixture with air and fluid amplifier means adapted to control fuel flow to said nozzle in accordance with variations in a fluid signal responsive to engine operating conditions.

This invention relates to fuel systems and is particularly directed to fuel systems utilizing fluid amplifier technology.

Because spark ignition internal combustion engines are quite sensitive to the proporations of the air-fuel mixture in the combustion chamber, innumerable systems have been developed in attempts to supply the engine with an air-fuel mixture proper for the various operating conditions. The systems in common use, however, include a venturi located in the air inlet to create a pressure signal which varies with the rate of air flow to the engine; this pressure signal determines the rate at which fuel is delivered to the engine.

Unfortunately however, the venturi signal does not vary linearly with air flow and thus is very weak at low air flow rates. This weak signal would result in insufficient fuel delivery to the engine. For this reason, the fuel systems which have a venturi to control fuel delivery generally also include separate arrangements to deliver fuel when the engine is idling and requires only a low rate of air flow.

This invention makes unnecessary a separate idle fuel delivery system by providing means for amplifying the signal which indicates the air flow rate. Using the principles of the recently announced fluid amplifiers, weak control signals such as venturi pressure are amplified to produce control signals strong enough to meter and deliver sufiicient fuel through the :main delivery nozzle.

As more extensively discussed in recent literature, Control Engineering of January 1963, for example, a fluid amplifier uses a relatively weak control signal to deflect the path of a fluid stream. Because relatively large deflections in the fluid path are obtained with weak control signals, a more sensitive control function is obtained by measuring the deflections of the path rather than by directly measuring the control signal.

This invention provides a fuel system in which such a fluid amplifier operates on a control signal based upon engine operating conditions and supplies fuel in accordance with the amplified signal. The drawing illustrates one embodiment of a fuel system which has a fluid amplifier to control enrichment of the air-fuel mixture supplied by the main metering system. In the disclosed fuel system carburetor, air flow to the engine creates a venturi pressure signal which controls a stream of air pumped through a fluid amplifier to create an amplified air flow signal. This amplified air flow signal controls a pressure esponsive fuel metering valve which delivers additional fuel to the main delivery nozzle at low air flow rates. Thus, a separate idle fuel delivery system is unnecessary, and in addition, more accurate control of the air-fuel mixture ratio is achieved.

Further, this invention provides means for varying the amplifier control signal so that fuel metering is not solely 3,388,898 Patented June 18, 1968 dependent on the air flow through a venturi. In the illustrated embodiment, a valve responsive to manifold vacuum controls an air bleed to alter the venturi pressure signal and provide a modified control signal for the fluid amplifier. The fuel metering valve, which responds to the amplified air flow signal as modified, delivers additional fuel to the main delivery nozzle to enrich the mixture for acceleration and maximum power operation.

The details as Well as other objectives and advantages of this invention are disclosed in the following description and in the accompanying drawing in which:

FIGURE 1 illustrates a fuel system carburetor embodying this invention; and

FIGURE 2 graphically illustrates the fuel metering characteristics of this invention.

Referring to the drawing, a carburetor 10 has an air inlet 12 controlled by a throttle 14 in the customary manner. A venturi 16 provides a restriction within air inlet 12 which reduces the pressure of the air flow therethrough to create a control signal related to the rate of air flow.

A fuel bowl chamber 18 is controlled by a float 20 in the customary manner to maintain a relatively constant level of fuel within the bowl. During engine operation, fuel is drawn from fuel bowl 18 through a main watering orifice 22, a chamber 24, and a passage 26 to the fuel inlet nozzle 29 in venturi 16.

With the construction so far described, the carburetor provides a fuel-air mixture graphically described by the single orifice curve of FIGURE 2. It will be noted that at low air flow rates, the engine requirements curve exceeds that provided by the single orifice construction. To provide an enriched mixture, a second orifice 28 is controlled to meter additional fuel under prescribed conditions.

Orifice 28 is controlled by a valve 30 which is secured to a pressure responsive diaphragm 32. Valve 30 and diaphragm 32 are biased in the valve opening direction by a spring 34. Atmospheric pressure is applied through a passage 36 against diaphragm 32 in a valve opening direction.

Air pump 38 is connected to an inlet 40 which opens into an interaction region 41 of a fluid amplifier indicated generally by 42. Air flow from pump 38 provides a stream of air through amplifier 42 which is issued along a predetermined path within interaction region 41 and which has a predetermined energy state. The air stream is discharged from interaction region 41 through outlets 44 and 46. With the amplifier construction so far described, the proportion of air discharged through outlet 44 and thus the pressure in outlet 44 is determined by the location of the splitter 48.

As air flows through the carburetor inlet 12 and the venturi 16, a pressure drop is produced to create a signal which is transferred through a passage to a regulating or control port 52 in the amplifier 42. This pressure signal at control port 52 has an energy state much lower than that of the air stream issued from inlet 40 but deflects the air stream to change the proportion of air discharged through outlet 44. As air flow through the carburetor inlet 12 increases, the pressure in venturi 16 drops further; this reduced pressure sensed at control port 52 deflects more of the air flow through amplifier 42 to outlet 44 and increases the pressure in outlet 44.

Outlet 44 is connected through a passage 54 to a chamber 56 so that the pressure in outlet 44 is applied against diaphragm 32 in a valve closing direction.

In operation, therefore, air flow through the carburetor air inlet 12 and venturi 16 creates a pressure signal related to the rate of air flow. Amplifier 42 operates on the signal to produce an amplified signal of air flow through outlet 44 which is still related to air flow through the carburetor air inlet 12. At low air flow rates, a relatively low pressure exists in chamber 56 and diaphragm 32 opens valve 28 to allow fuel metering through the parallel orifices 28 and 22. As air flow increases, the pressure in chamber 56 increases and diaphragm 32 causes valve 30 to close orifice 28 so that fuel is metered only through orifice 22. The fuel-air ratio achieved by such a metering system is graphically illustrated in FIGURE 2. It should be noted that the mixture ratio achieved by this metering system very closely approximates the mixture ratio required by the engine.

The diaphragm controlled valve 30 and orifice 28 may also be used to provide an enriched mixture whenever acceleration or maximum power is required of the engine. To accomplish this, a separate valve 60 controls an atmospheric bleed 62 connected to the venturi sign-a1 passage 50. Valve 60 is secured to a diaphragm 64. Manifold vacuum existing in inlet 1'2 below throttle 14 is applied against diaphragm 64 through a passage 66. Under normal engine operation when an economy mixture is required, manifold vacuum pulls diaphragm 64 to the right against the bias of a spring 68 and closes valve 60. When the manifold vacuum drops below a pre-determined value, such as will occur during acceleration or when maximum power is required, diaphragm 64 opens valve 60 to ad mit atmospheric pressure to passage 50. The venturi vacuum signal indicative of air flow is thus reduced, so that regulating port 52 receives a modified pressure signal. Air flow through fluid amplifier outlet 44 is reduced, and concomitantly the pressure in chamber 56 is reduced. Diaphragm 32 then raises valve 30 to allow fuel metering through the parallel orifices 28 and 22.

This invention provides a simple and inexpensive ar rangement for amplifying signals based on engine operating conditions so that an enriched air-fuel mixture may be accurately and efliciently metered and delivered to the engine. It will be appreciated by those skilled in fuel system and fluid amplifier technologies that this invention may 'be utilized in many other arrangements to supply fuel to an engine.

I claim:

1. An internal combustion engine fuel system comprising:

a nozzle adapted to discharge fuel for mixture with air,

fluid amplifier means having:

an interaction region and including an inlet port opening into said interaction region,

a source of regulated fluid connected to said inlet port to issue a fluid stream along a predetermined path Within said interaction region, said fluid stream having a predetermined energy state and passing through said interaction region without change of phase,

a source of regulating fluid supplying fluid the characteristics of which provide a fluid signal having an energy state substantially lower than the energy state of the fluid stream,

connecting means for transmitting the fluid signal from said source of regulating fluid to said interaction region to cause a variation in the path of the fluid stream within said interaction region, said connecting means including:

passage means through which the fluid signal is transmitted from said source of regulating fluid and valve means associated with said passage means and operative in accordance with an engine demand for fuel for controlling the transmission of the fluid signal therethrough, said amplifier means further including:

outlet means opening from said interaction region for receiving the fluid stream and establishing a regulated fluid condition which varies in accordance with variations in the path of the fluid stream,

and means for delivering fuel to said nozzle in accordance with the regulated fluid condition.

2. The fuel system of claim 1 which further includes an air inlet for air flow to the engine and a throttle for con trolling air flow through said air inlet and wherein said valve means is responsive to the pressure in said air inlet downstream of said throttle.

3. The fuel system of claim 2 wherein said source of regulating fluid comprises a source of air providing a substantially atmospheric fluid pressure signal and wherein said valve means controls the transmission of said pressure signal through said passage means to said interaction region to cause a variation in the path of the fluid stream which establishes a fluid condition in said outlet means leading to an increased rate of fuel flow to said nozzle when the pressure in said inlet downstream of said throttle increases above a predetermined level.

4. An internal combustion engine fuel system comprising:

a nozzle adapted to discharge fuel for mixture with air,

fluid amplifier means having:

an interaction region and including an inlet port opening into said interaction region,

a source of regulated fluid connected to said inlet port to issue a fluid stream along a predetermined path within said interaction region, said fluid stream having a predetermined energy state,

a first source of regulating fluid connected to said interaction region,

a second source of regulating fluid,

passage means connecting said second source to said interaction region, said first and second sources supplying fluid the characteristics of which provide first and second fluid signals which combine to produce a resultant fluid signal indicative of an engine demand for fuel and having an energy state substantially lower than the energy state of the fluid stream and which causes a variation in the path of the fluid stream within said interaction region,

said amplifier means further including:

outlet means opening from said interaction region for receiving the fluid stream and establishing a regulated fluid condition which varies in accordance with variations in the path of the fluid stream,

and means for delivering fuel to said nozzle in accordance with the regulated fluid condition.

5. The fuel system of claim 4 wherein said first source of regulating fluid comprises an air inlet for air flow to the engine and venturi means in said air inlet providing a fluid pressure signal indicative of the rate of air flow to the engine and wherein said second source of regulating fluid comprises a source of air providing a substantially atmospheric fluid pressure signal and wherein said fluid pressure signals combine to produce a resultant fluid pressure signal of intermediate pressure.

6. An internal combustion engine fuel system comprising:

a nozzle adapted to discharge fuel for mixture with air,

fluid amplifier means having:

an interaction region and including an inlet port opening into said interaction region,

a source of regulated fluid connected to said inlet port to issue a fluid stream along a predetermined path within said interaction region, said fluid stream having a predetermined energy state,

a source of regulating fluid connected to said interaction region and supplying fluid the characteristics of which provide a fluid signal indicative of an engine demand for fuel and having an energy state substan- 3 tially lower than the energy state of the fluid stream and which causes a variation in the path of the fluid stream within said interaction region,

said amplifier means further including:

outlet means opening from said interaction region for receiving the fluid stream and establishing a regulated fluid condition which varies in accordance with variations in the path of the fluid stream,

a source of fuel,

passage means extending from said source of fuel to said nozzle,

valve means associated with said passage means for controlling fuel flow therethrough,

and means for operating said valve means in response to variations in the regulated fluid condition to thereby control fuel flow in response to variations in the fluid signal.

7. The fuel system of claim 6 wherein said source of regulating fluid comp-rises an air inlet for air flow to the engine and venturi means in said air inlet providing a fluid pressure signal indicative of the rate of air flow therethrough and wherein said passage means extending from said source of fuel to said nozzle includes first and sec- 6 0nd parallel fuel metering orifices and wherein said valve means controls fuel flow through one of said orifices.

8. The fuel system of claim 7 wherein said outlet means establishes a pressure condition in a given relation to air flow through said air inlet and wherein said means for operating said valve means comprises means responsive to the pressure condition in said outlet means for opening said valve means at pressure conditions below a predetermined level to provide an enriched mixture of fuel in air at low rates of air fiow through said air inlet.

References Cited UNITED STATES PATENTS 3,001,539 9/1961 Hurvitz 137-815 3,215,413 11/1965 Szwargulski et a1. 261-69 X 3,258,023 6/1966 Bowles 137-81.5

FOREIGN PATENTS 1,257,050 2/ 1961 France.

694,387 7/ 1953 Great Britain. 289,804 3/ 1953 Switzerland.

HARRY B. THORNTON, Primary Examiner.

TIM .R. MILES, Assistant Examiner. 

